PROJECT SUMMARY/ABSTRACT Chemotherapy-induced peripheral neuropathy (CIPN) is a major side effect of many efficacious anticancer drugs, including platinum drugs, taxanes, proteasome inhibitors, vinca alkaloids, epothilones, and immunomodulators. Their neurotoxic side effects can be so debilitating that treatment may need to be reduced or stopped. However, unlike other major side effects of chemotherapy (e.g. nausea, hair loss, bone marrow failure), no standard, effective treatments exist to prevent or reverse CIPN. This is largely because the cellular mechanisms for CIPN have not been identified and the symptoms of CIPN including numbness, decreased blood flow to extremities, loss of proprioception, loss of tendon reflexes, pain, allodynia, and/or increased sensitivity to cold vary greatly in patients. Because CIPN is debilitating and may be irreversible, identification of key targets to prevent neurotoxicity without compromising the tumor-killing effects of anticancer drugs is critical in developing a first-in- class therapeutic that can directly affect a patient's ability to receive optimal treatment. Our previous studies examining the hypothesis that DNA damage of sensory neurons contributes to CIPN laid the foundation for the proposed work, which is poised to develop a drug candidate. We demonstrated that reducing DNA base excision repair (BER) activity by reducing expression of the apurinic/apyrimidinic endonuclease/redox factor (APE1) augmented the neurotoxicity produced by anticancer treatment, whereas supplementing APE1's repair activity attenuated the neurotoxicity. It is likely that, in non-dividing cells like neurons, DNA damage could alter the function of sensory neurons in ways that manifest as the symptoms observed in CIPN. Consequently, DNA repair would be critical for proper genetic expression of the right types and amounts of proteins, a crucial element of genomic maintenance. For the proposed studies, we will examine whether augmenting APE1 repair activity in vivo will prevent chemotherapy-induced alterations in sensory neuronal function (manifested as CIPN) without jeopardizing the cancer treatment. Using tumor bearing mice, we will examine whether a small molecule (E3330) which was identified to enhance APE1's DNA repair function in neurons can prevent (aim 1) or reverse (aim 2) DNA damage and alterations in the function of sensory neurons caused by cisplatin, oxaliplatin or carboplatin. Furthermore, we will examine whether the small molecule (E3330) will compromise the anticancer efficacy of the platinum drugs by examining DNA damage and tumor survival following treatment (aim 3). Because E3330 has been found to act as a single agent and in combination with other cancer therapeutic drugs to decrease tumor cell growth, this molecule has the potential to offer a ?win-win? scenario; block tumor cell growth while protecting against neuronal dysfunction. Additionally, E3330 will enter a phase 1 clinical trial for solid tumors followed by phase 1b/phase 2 trials for various indications that include platinums in their SOC (e.g. colon, pancreatic). Therefore, it requires further preclinical study using an in vivo paradigm to demonstrate effectiveness in the context of neuronal protection and CIPN models.